This invention relates to a transfer sheet and to a process using the same for producing decorative articles.
As a method of printing, transfer printing (decalcomania) which is carried out with the use of a transfer sheet is known. A transfer sheet of very general type comprises a substrate, a release layer, and a printed layer. In addition, as desired, a protective layer for protecting the printed layer, a layer of an adhesive, and/or the like are provided after transferring.
Transfer sheets of this character are used for printing on various materials and articles such as artificial leather, soft vinyl chloride resin, plywood, ceramic articles, metals, and glass. Particularly in cases such as that wherein printing is carried out on an article having a material or shape which makes direct printing difficult to obtain clear printed patterns and the case where the number of impressions to be printed at one time is small, and, moreover, the number of patterns is large, the transfer printing method in which transfer sheets are used is convenient because a saving can be made in the time of printing itself and the time for handling after printing, and it is not necessary to change plates for changes in patterns.
Almost all of the printing performed heretofore on printed articles by the transfer printing method with the use of transfer sheets has given flat patterns. Where it is desired to obtain a pattern projecting from the surface of an article printed by transfer printing, it is a common practice to resort to a method such as that wherein an ink having a high solid content is used when forming the pattern on the transfer sheet or printing is carried out by a printing method in which the ink transfer quantity is great.
However, when an ink of high solid content is used, the viscoelasticity of the ink varies, which is not desirable from the standpoint of printability. A printing method in which the ink transfer quantity is great such as, for example, silk-screen printing, intaglio printing, or gravure printing in which the cell depth is great, is disadvantageous in that the rate of drying after printing is low. Furthermore, when the transfer sheet is produced by the sheet-fed printing method and piled or when it is produced by the rotary method and wound up, crushing of the printed pattern, deformation of the substrate, and other problems occur.
A transfer sheet used in the production of foamed flooring materials and the like and provided with a foaming inhibiting or suppressing pattern has heretofore been known. However, when a known transfer sheet provided with a foaming inhibiting pattern is used for producing a decorative article having a large area of depressed or concave parts, it is necessary to prepare the transfer sheet by using a great quantity of an expensive foaming inhibitor compound. Moreover, the transfer sheet thus obtained has a number of drawbacks such as its undergoing blocking after being wound up and its unsuitability for patterns of small area of projecting or convex parts. Furthermore, while concave parts of a low degree of foaming which are depressed from the surface after foaming could be produced even by the utilization of this transfer sheet, convex parts projecting from the surface after foaming could not be provided heretofore.